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Move libpq's write_failed mechanism down to pqsecure_raw_write().
Commit1f39a1c06
implemented write-failure postponement in pqSendSome, which is above SSL/GSS processing. However, we've now seen failures indicating that (some versions of?) OpenSSL have a tendency to report write failures prematurely too. Hence, move the primary responsibility for postponing write failures down to pqsecure_raw_write(), below SSL/GSS processing. pqSendSome now sets write_failed only in corner cases where we'd lost the connection already. A side-effect of this change is that errors detected in the SSL/GSS layer itself will be reported immediately (as if they were read errors) rather than being postponed like write errors. That's reverting an effect of1f39a1c06
, and I think it's fine: if there's not a socket-level error, it's hard to be sure whether an OpenSSL error ought to be considered a read or write failure anyway. Another important point is that write-failure postponement is now effective during connection setup. OpenSSL's misbehavior of this sort occurs during SSL_connect(), so that's a change we want. Per bug #17391 from Nazir Bilal Yavuz. Possibly this should be back-patched, but I think it prudent to let it age awhile in HEAD first. Discussion: https://postgr.es/m/17391-304f81bcf724b58b@postgresql.org
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@@ -777,19 +777,19 @@ definitelyFailed:
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* (putting it in conn->inBuffer) in any situation where we can't send
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* all the specified data immediately.
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*
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* Upon write failure, conn->write_failed is set and the error message is
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* saved in conn->write_err_msg, but we clear the output buffer and return
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* zero anyway; this is because callers should soldier on until it's possible
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* to read from the server and check for an error message. write_err_msg
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* should be reported only when we are unable to obtain a server error first.
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* (Thus, a -1 result is returned only for an internal *read* failure.)
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* If a socket-level write failure occurs, conn->write_failed is set and the
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* error message is saved in conn->write_err_msg, but we clear the output
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* buffer and return zero anyway; this is because callers should soldier on
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* until we have read what we can from the server and checked for an error
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* message. write_err_msg should be reported only when we are unable to
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* obtain a server error first. Much of that behavior is implemented at
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* lower levels, but this function deals with some edge cases.
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*/
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static int
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pqSendSome(PGconn *conn, int len)
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{
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char *ptr = conn->outBuffer;
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int remaining = conn->outCount;
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int oldmsglen = conn->errorMessage.len;
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int result = 0;
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/*
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@@ -817,7 +817,7 @@ pqSendSome(PGconn *conn, int len)
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if (conn->sock == PGINVALID_SOCKET)
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{
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conn->write_failed = true;
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/* Insert error message into conn->write_err_msg, if possible */
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/* Store error message in conn->write_err_msg, if possible */
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/* (strdup failure is OK, we'll cope later) */
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conn->write_err_msg = strdup(libpq_gettext("connection not open\n"));
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/* Discard queued data; no chance it'll ever be sent */
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@@ -859,24 +859,6 @@ pqSendSome(PGconn *conn, int len)
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continue;
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default:
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/* pqsecure_write set the error message for us */
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conn->write_failed = true;
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/*
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* Transfer error message to conn->write_err_msg, if
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* possible (strdup failure is OK, we'll cope later).
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*
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* We only want to transfer whatever has been appended to
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* conn->errorMessage since we entered this routine.
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*/
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if (!PQExpBufferBroken(&conn->errorMessage))
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{
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conn->write_err_msg = strdup(conn->errorMessage.data +
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oldmsglen);
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conn->errorMessage.len = oldmsglen;
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conn->errorMessage.data[oldmsglen] = '\0';
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}
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/* Discard queued data; no chance it'll ever be sent */
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conn->outCount = 0;
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@@ -886,7 +868,18 @@ pqSendSome(PGconn *conn, int len)
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if (pqReadData(conn) < 0)
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return -1;
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}
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return 0;
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/*
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* Lower-level code should already have filled
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* conn->write_err_msg (and set conn->write_failed) or
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* conn->errorMessage. In the former case, we pretend
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* there's no problem; the write_failed condition will be
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* dealt with later. Otherwise, report the error now.
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*/
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if (conn->write_failed)
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return 0;
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else
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return -1;
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}
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}
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else
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